Simplify IRTEntry

We previously stored the last several object references associated
with indirect reference table entry. The old entries might once have
been used to provide more informatio about stale entries. But with a
copying collector, they were not even getting updated during GCs,
and we could not identify any purpose for them. Keep just the current
entry instead.

We keep the serial number from before to continue to check for stale
references.

This should save nearly half the space (both used and reserved) in
indirect reference tables, while slightly speeding up accesses.
It implements the most basic option suggested in the bug. If this
pays off in a noticable way, we should do more here.

Test: Build and boot AOSP
Bug: 184847225
Change-Id: If563bcfcf7a01e4551326f06a2894bd906947025

0 files changed, 0 insertions, 0 deletions